BlitzBlast
Busy with School
Secret bosses generally aren't even fought by most people who play the game. Hell, some people who say they "played" an RPG might not have even fought the final boss.
Most people playing FF III DS don't even get to fight the secret boss anyways; it requires you to do an inane Nintendo Wi-Fi letter exhanging process around 8 times.
And that's just for the secret boss; in total you'll need to do it around 20 times or so for everything.